In this post, I’ll contrast and compare the different management and provisioning path architectures between Citrix on Nutanix AHV using Machine Creation Services (MCS) and two leading VMware Horizon options. While there is always numerous options within deployments the examples here will be based on the best and leading alternatives. I’ve prepared a 5,000 and 25,000 user examples to illustrate how a common sized environment would look versus one at a larger scale. This will display the difference in how things scale and whether complexity increases or remains low.

The reason to look at this is to help understand how failures, patching, upgrades and human error might affect the resiliency of the provisioning path and management interface. If the control plane is down for the underlying hypervisor the VDI broker layer will not be able to provision or manage the desktop VMs. This can have serious implications for users as they may be unable to access resources if they are disconnected or logoff and when they return there are not enough available desktops due to a control plane issue.

On the operations side, this is an important discussion also, because organizations demand simplicity in architectures. They do not want solutions that are complex to set up and maintain. So I will also look at how many management interfaces the alternatives impose on admins and point any areas of concern.

Citrix + AHV 5,000 User Example

In the first example, we are looking at 5,000 XenDesktop users deployed on Nutanix AHV hypervisor. XenDesktop communicates directly to the AHV cluster via the Prism cluster IP address and utilized API calls to perform actions. Prism is the distributed management interface and runs as a service in the Nutanix controller VM (CVM) on each node. This means that Prism is always available during upgrades and should a node, CVM or a service fail one of the other nodes will accept incoming connections to Prism and API calls.

In the sample diagram below I’m showing XenDesktop connecting to a single AHV cluster running all 5,000 desktop VMs. This is to showcase the power and flexibility that AHV and Prism provide. AHV does not have a maximum cluster size limit like legacy hypervisors impose. With Prism running on every node in the cluster the management and provisioning operations for VMs and the cluster scale out linearly with the cluster. This means that there is no difference in the performance of provisioning or management operations whether a cluster is 3 nodes or 80 nodes. This allows architects to design for large clusters when applicable without any concerns over imposed cluster size limitations.

Should there be valid reasons the 5,000 desktops could be split into more than one cluster. Reasons for doing so might be workloads that don’t mix well or adversely affect desktop density or the desire to divide into distinct failure domains.

Pros:

No Single Point of Failure (SPOF) for provisioning or management

Node or VM counts do not limit cluster sizes

Linear performance of control plane

Highly available control plane and provisioning path

Simple architecture that easy to deploy, manage and operate

Cons:

VMware Horizon does not support AHV

VMware Horizon 5,000 user example

In this first VMware Horizon example, we are looking at the classic way of deploying vCenter server. This scenario does not matter if you deploy Windows or vCenter appliance variations. In this classic method vCenter is a single point of failure (SPOF). This means that the environment can be severely impacted during upgrades and failures that take vCenter offline for more than a few minutes.

Another significant constraint to call out is that VMware does not recommend building blocks of infrastructure that host more than 2000 desktops. This means that each block will consist of a vCenter server and one or more vSphere clusters. In our 5,000 user example, this architecture forces us to have 3 vCenters and the number of clusters below them is open to how the architect wants to design based on requirements. By limiting the scale of each vCenter, VMware is keeping the performance and responsiveness within acceptable limits. But this approach, when scaled becomes inefficient because you are using additional resources and the number of items to manage and update continues to scale as you add users.

Pros:

Fairly simple to deploy and is well understood after long VMware history

Widely supported by applications

Cons:

vCenter is Single Point of Failure (SPOF)

vCenter is limiting factor of 2,000 desktops per vCenter

VMware composer SPOF for linked clone provisioning

VMware Horizon 5,000 user example w/vCenter HA

This example is just an alternative to the previous one in that I’ve inserted the new vCenter High Availability (HA) option that was released in vSphere 6.5 recently. The vCenter Server Appliance (vCSA) must be utilized if you want to use this HA option. The sizing and architectures are the same. The primary difference is the availability of vCenter in this alternative. To deploy the vCenter HA config you are required to deploy 3 vCSA VMs for each vCenter that you want to be highly available. There will be an active, passive and witness VM in each deployment. Multiply this out with the three blocks required to deliver 5,000 users and we now have nine vCenter appliances to deploy, manage and upgrade.

This adds a lot of complexity to the architecture for the benefit of increasing the resiliency of the provisioning path and management plane.

vCenter is still limiting factor for 2,000 desktop VM limit per vCenter

As design scales complexity increases by having so many management points

Citrix + AHV 25,000 User Example

In this and the following examples, I have now scaled the number of users to 25,000 to see what effects this has on the different architectures and management experience. For the Citrix and AHV architecture, nothing changes here other than the number of users. Citrix can accommodate the large number of users within a single deployment. On the AHV cluster side of things, I have elected to evenly divide the users between four different clusters. I could have chosen a single cluster but that felt extreme, architects can also choose more clusters if that meshes with their requirements. Within Citrix Studio, each AHV cluster will be configured as an endpoint that can be provisioned against.

The point is that in the architecture organizations can accommodate large numbers of users with a small number of clusters of which all benefit from highly available provisioning and management controls. Each AHV cluster can be managed via the Prism interface built into the cluster or a Prism Central can be deployed to allow for global management and report. An important thing to note is that Prism Central is not in the provisioning path so does not have any effect on our architecture explained earlier.

Pros:

No cluster size limits provides flexibility to account for budget savings and ability to meet requirements.

Highly available architecture at all levels with simplicity baked in.

Small number of clusters reduces node counts by saving on the number of HA nodes for additional clusters.

VMware Horizon 25,000 User Example

Now taking a look at the expanded user environment with VMware Horizon architecture you can see that I’m showing the vCenter HA alternative. I think that if you have the option for a highly available control plane most will select that option so I’m not showing the classic single vCenter option.

The architecture is the same but you will notice a few things now that the user count has been scaled up to 25,000. We can no longer deliver that many users from a single Horizon installation (Pod). The maximum users within a pod are 10,000 so we now require three Horizon installs to meet our user counts. To be honest having three Horizon pods does affect the broker management experience but in this scenario has really no bearing on the cluster count or design.

Following the 2,000 users per vCenter rule we will need 13 vCenters to meet our 25,000 user requirement. To keep things clean the diagram shows just a single cluster attached to each vCenter but the 2,000 users could be split between a few clusters under each vCenter if that made sense.

You can see from the diagram that deploying 13 vCenters in HA configuration requires 39 vCenter appliances to be deployed and configured. Yes that’s right, Thirty-nine!! Just think about the complexity this adds to troubleshooting and upgrades. Each one of those appliances must be upgraded individually and within a short window to not break functionality or support. Upgrades now may force you to upgrade Horizon, Horizon agents, clients, vCenter and vSphere all within a single weekend. That’s a lot of work, best you could do is do one of the pods per weekend and now you’re exposing your staff to three weeks of overtime and loss of their weekends.

vCenter is still limiting factor for 2,000 desktop VM limit per vCenter

Three vCenter linked mode view to see entire infrastructure view

Three different Horizon management consoles to configure and control users

Composer is an SPOF for linked clone provisioning per Horizon Pod

VMware Horizon 25,000 users on VxRail

In this last example, we are going to adjust the previous example and look at what would change if it was deployed on VxRail appliances that utilize VSAN for storage. The Horizon and vCenter / vSphere architecture would be the same the only thing to highlight is what is added by VxRail.

Each of the clusters that provide resources for each 2,000 user block would be a VxRail cluster. These clusters have a VxRail virtual appliance VM that runs on it and is used for appliance management and upgrades. Given this scale, we now see that each of the 13 clusters will have its own dedicated VxRail manager and does not offer a global management function that Prism Central offers. VxRail manager is not in the provisioning path, but does add to the complexity of managing this type of deployment and should be considered before selecting.

Pros:

Same as previous example

Cons:

Same as previous example

13 Different VxRail managers adds needed complexity

VxRail is an SPOF as a single VM running on each cluster for management operations

Conclusion

Just to wrap up my thoughts and examples here is that whether you’re designing a small or large scale VDI environment it’s important to understand how the management and provisioning structures will function. These are important to how highly available the solution is and what level of effort will be required to support it from day 2 and on. The resiliency and simplicity that Citrix offers when connect to Nutanix AHV cannot be rivaled by any other alternatives today.

Brian is a VCDX5-DCV and a Sr. Tech Marketing Engineer at Nutanix and owner of this website. He is active in the VMware community and helps lead the Chicago VMUG group. Specializing in VDI and Cloud project designs. Awarded VMware vExpert status 6 years for 2016 - 2011. VCP3, VCP5, VCP5-Iaas, VCP-Cloud, VCAP-DTD, VCAP5-DCD, VCAP5-DCA, VCA-DT, VCP5-DT, Cisco UCS Design

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In this post I will take a quick tour through the process of managing virtual machines running on Nutanix Acropolis Hypervisor (AHV). This will touch on the basics and the most common tasks that admins are performing on VMs that already exist. All VM management tasks will be performed from within Prism the single management interface for Nutanix clusters. The VM view within Prism is where the majority of VM-based tasks are performed. A table based view provides an easy to consume method of finding and managing your virtual machines. When selecting a VM, just below the table will be a group of actions that can be taken. These are highlighted in the image below.

Brian is a VCDX5-DCV and a Sr. Tech Marketing Engineer at Nutanix and owner of this website. He is active in the VMware community and helps lead the Chicago VMUG group. Specializing in VDI and Cloud project designs. Awarded VMware vExpert status 6 years for 2016 - 2011. VCP3, VCP5, VCP5-Iaas, VCP-Cloud, VCAP-DTD, VCAP5-DCD, VCAP5-DCA, VCA-DT, VCP5-DT, Cisco UCS Design

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When it comes to building out a new Acropolis (AHV) cluster you are either starting out with new VMs or looking to migrate existing VMs from a vSphere environment. I have covered the process of creating new VMs in the “Creating VMs on AHV” post in this series. But if you are moving from vSphere to AHV, then there are two challenges that must be planned for. The first one is what will the conversion process look like and second, what will the migration process look like. With each of these are multiple choices and it will be up to the project team to decide which is the best choice for the project. There are likely other options that I might not mention here either.

Converting vSphere VMs

The task of converting a vSphere VM to a VM that runs on AHV is not that different than other hypervisors or even the P2V days when you were moving from physical servers. You have a VM that is in a vSphere format and must be converted to a different format. It will also have VMware tools and drivers installed into the operating system. After the conversion these will need to be cleaned up, just like they would be when migrating to other platforms.

For this there potentially two viable candidates. The first would be grabbing the virtual disk file (VMDK) from a datastore and using the image management feature in AHV to import and convert the disk. There would still be cleanup to be done, but it’s a simple one-off way. This method would not be ideal for doing a bunch of VMs, it however might be a simple method if you just have a hand full of template VMs that you want to populate on the new cluster.

The second and leading choice is to use the following method. In short with this method you are installing the VirtIO drivers in advance, think of them as the drivers that VMware tools install. Storage vMotion the VMs to a shared Nutanix datastore, power off the VM and create a new VM on AHV using the vDisks that were moved over. A fellow Nutant and VCDX has already created a detailed blog post about converting a vSphere VM to run on AHV. You can read the full details here as written by Artur Krzywdzinski.

In the future I would like to see something like Double-Take offer a solution that would offer help with these cross-platform conversions and migrations. This is something they have working for cloud migrations today. I see this becoming a common task in the future and demand is only going to increase for organizations wanting to move workloads between different resource pools whether they are on-premises or off-premises and very few of these moves will support a single VM format.

Migrating the VMs

The conversion process was just covered for what is available at the time this was published. I also touched on the option of sharing out a datastore from the AHV cluster to an existing vSphere cluster. This would allow you to Storage vMotion any VMs to that shared datastore before shutting them down to complete the conversion process. This method will likely be the most heavily used, since its familiar for other legacy types of migrations between old and new infrastructure.

A second option is available if both the vSphere and AHV clusters are running on Nutanix gear. You can create a Protection Domain (PD) on the vSphere cluster to replicate all of the VMs to the AHV cluster. This will get the data over to the AHV cluster in an efficient manner, this would be a great option if moving between sites also.

Brian is a VCDX5-DCV and a Sr. Tech Marketing Engineer at Nutanix and owner of this website. He is active in the VMware community and helps lead the Chicago VMUG group. Specializing in VDI and Cloud project designs. Awarded VMware vExpert status 6 years for 2016 - 2011. VCP3, VCP5, VCP5-Iaas, VCP-Cloud, VCAP-DTD, VCAP5-DCD, VCAP5-DCA, VCA-DT, VCP5-DT, Cisco UCS Design

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Live migration is the ability to move a running VM from one host (node) to another without any downtime or loss of connectivity. Some vendors call this live migration, if your a VMware person this is known as a vMotion. Live migration is supported on an Acropolis Hypervisor (AHV) cluster, whether it is initiated manually or through an automatic process.

There are several ways for VMs to be live migrated to other hosts, the most common is for someone to use Prism to select the VM and choose to migrate it. They can also occur when a host is placed in maintenance mode which evacuates all VMs, from the Acropolis CLI or via the REST API.

How to live migrate an AHV VM

Acropolis managed virtual machines can be manually migrated to other hosts within the cluster through the VM portion of the Prism interface. First you select VM option from the top menu. Then choose the table view, then select VM to be moved and click the migrate option.

The migration action window will present the admin with the option to let the system automatically select the target host based on resource utilization or via the drop down option, allow the admin to manually select the target host from the list of nodes in the cluster.

The following image shows that you can easily select the target host to move the VM to, if you do not want to let the system make the selection for you. Click the Migrate button and the VM is on its way to the new host.

API Migrate Option

I still have very little experience with API’s but wanted to show that the option is available.

ACLI Migrate Option

The ACLI option offers the ability to specify a max bandwidth for the move along with the expect destination options.

Conclusion

I know that live migrating a VM is pretty boring these days as it should be. But educating the community that this feature is available and showing how easy and flexible it is to use is also need.

Brian is a VCDX5-DCV and a Sr. Tech Marketing Engineer at Nutanix and owner of this website. He is active in the VMware community and helps lead the Chicago VMUG group. Specializing in VDI and Cloud project designs. Awarded VMware vExpert status 6 years for 2016 - 2011. VCP3, VCP5, VCP5-Iaas, VCP-Cloud, VCAP-DTD, VCAP5-DCD, VCAP5-DCA, VCA-DT, VCP5-DT, Cisco UCS Design

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I started my life in IT with MS-DOS and then moved into Windows when that became a thing. Then the wonders of VMware were introduced to me about a decade ago and I never looked back. Along the way, I have had limited exposure to Linux and related systems and it was always something that I wanted to learn more about, but other things always came first.

Since joining Nutanix recently, I will be learning a lot more about the Acropolis Hypervisor (AHV) offering that is built from KVM roots. This will be a new challenge for someone with my background and I’m looking forward to it. To help others with a similar background, I thought that a series of blog posts covering topics on getting started and operational tasks would be a good place to begin. These posts should help others that are new to virtualization or are experienced with VMware vSphere or Hyper-V already.

In the upper right margin of each post is an index of the posts in this series for easier access.

If there are other topics that you would like to see, drop me a note in the comments or via another method and I’ll consider it. If this series is well received I may do an Advanced AHV series at a later date.

Brian is a VCDX5-DCV and a Sr. Tech Marketing Engineer at Nutanix and owner of this website. He is active in the VMware community and helps lead the Chicago VMUG group. Specializing in VDI and Cloud project designs. Awarded VMware vExpert status 6 years for 2016 - 2011. VCP3, VCP5, VCP5-Iaas, VCP-Cloud, VCAP-DTD, VCAP5-DCD, VCAP5-DCA, VCA-DT, VCP5-DT, Cisco UCS Design